Solenoid Contactor Driver With Switchable Fast Discharge Path
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Solution Overview
Problem
Existing high-voltage contactor drivers face challenges with slow de-energization, leading to potential damage and safety hazards due to unsuitable freewheel paths and low clamping voltage limitations, which increase production costs and area occupancy on circuit chips.
Innovation Solution
A driver system with a high-side and low-side power switch, controlled by a PWM controller, utilizing a Zener trigger for clamping and a switchable freewheel path to quickly discharge the solenoid, reducing the need for multiple power devices and allowing high-voltage clamping, while preventing safety hazards like short-to-ground activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a freewheel path is used to discharge the solenoid coil, then the design is simple, but the de-energization is slow causing contactor welding and safety hazards
Solution Approach 1:
The patent implements a dynamic discharge path selection mechanism where the system can switch between freewheel path and clamping path based on operational requirements. The controller selectively activates the clamping path during de-energization to achieve fast discharge, while maintaining the simple freewheel path structure for normal operation. This dynamic approach resolves the contradiction by providing both simplicity and fast de-energization when needed.
Solution Approach 2:
The patent introduces a clamping circuit as an intermediary component that provides an alternative discharge path for the solenoid coil. This clamping circuit, controlled by the controller, acts as a mediator that can quickly dissipate coil energy when fast de-energization is required, preventing contactor welding while maintaining the simplicity of the original freewheel path design.
2Speed
If a voltage clamping circuit with low clamping voltage is used, then the de-energization is fast, but it is unsuitable for high-voltage contactors and requires multiple power devices increasing area and cost
Solution Approach 1:
The patent makes the existing low-voltage clamping circuit multi-functional by enabling it to operate in both low-voltage and high-voltage modes. The controller selectively activates the clamping path for high-voltage contactors, allowing the same circuit architecture to serve both low-voltage and high-voltage applications. This eliminates the need for separate high-voltage clamping circuits and multiple power devices, reducing area and cost while maintaining fast de-energization capability.
Solution Approach 2:
The patent changes the operational parameters of the clamping circuit by dynamically controlling its activation based on voltage requirements. For high-voltage contactors, the controller enables the clamping path with appropriate voltage ratings, while for low-voltage applications, the same circuit operates in its original mode. This parameter-based approach allows a single circuit design to handle multiple voltage levels without requiring multiple specialized power devices.
3Reliability
If multiple power devices are used for high-voltage clamping, then high-voltage contactor control is achieved, but the chip area and production cost increase
Solution Approach 1:
The patent uses a simplified model approach where the clamping circuit is designed to work with externally provided high-voltage power devices rather than integrating all high-voltage components on-chip. The controller and clamping logic are implemented efficiently using standard cell libraries, creating a lightweight core that can be paired with various external power device configurations. This copying approach allows high-voltage control capability while minimizing chip area occupancy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables fast and safe de-energization of the solenoid, reducing contactor damage and manufacturing costs by occupying less chip area with lower voltage-rated power switches, ensuring efficient and safe operation of high-voltage contactors.
Implementation Method 1
The solenoid is coupled to a driving circuit which will apply a current through the coil of the solenoid resulting in electromagnetic induction. The magnetic force exerted on the plunger moves the contacting surfaces from an open to a closed position.
Implementation Method 2
A driver system with a high-side and low-side power switch, controlled by a PWM controller, utilizing a Zener trigger for clamping
Data Source
AI summary
A driver for driving an electromechanical device having a solenoid and a mechanical switch. The driver includes an input port, a ground port, first and second output ports connectable to the electromechanical device; and two power switches. A controller operates in a first mode to charge the solenoid and close the mechanical switch, a second mode to maintain the mechanical switch closed, and a third mode to discharge the solenoid and open the mechanical switch. In the first and second modes, the low-side power switch is on and the high-side power switch is controlled to switch between an on-state and an off-state by the controller. In the on-state a path is formed between the input port and ground via the high-side and low-side power switches, and the solenoid. In the off-state a path is formed between ground and ground via a ground diode, the solenoid and the low-side power switch.